A freshman Queens congresswoman learned a brutal lesson in the rough-and-tumble ways of Washington — not on the House floor, but on the street.

Rep. Grace Meng, New York’s first Asian-American congresswoman, was clocked on the head from behind by a mugger three blocks from the Capitol at about 8 p.m. Tuesday.

She told The Post she had just had dinner with a friend at a DC Eastern Market restaurant when the thug attacked her at Sixth Street and Pennsylvania Avenue.

“I went on my way and as I was walking, I got hit on the head,” she said. “And, honestly, I don’t remember anything after I got hit.”

Meng was left battered and bruised and sporting a huge bump on her head. According to cops, she was found “disoriented.”

The crook made off with her black Gucci tote bag and was still at large Wednesday night.

“The next thing I remember was waking up in an ambulance,” Meng said. “I did not see or hear anyone. Luckily, my phone and credit card were in my coat pocket. Very fortunate.”

Meng was taken by ambulance to George Washington University Hospital, where she underwent two CAT- scans, which showed no serious injury.

“I hope it was just a random act,” she said. “My injuries are not that serious.”

Despite the attack, the undeterred Flushing Democrat returned to her Capitol office Wednesday.

It was the first time she had been mugged.

“You know, I’m from New York City and I have not been mugged like that,” she said.

Meng has been unable to help cops with any description of her assailant.

“While this was a frightening ordeal, I fortunately was not seriously injured,” she said in a written statement.

“Obviously, things could have been much worse.”

Meng was elected in November 2012 to represent the 6th District in Queens.

A former state assemblywoman, she won 68 percent of the vote in the House race, despite an ongoing bribery case against her father, Jimmy Meng, who also served in the Assembly.

Jimmy Meng pleaded guilty to wire fraud and was sentenced this year to one month in prison.

Grace Meng’s GOP House opponent, City Councilman Daniel Halloran, was charged this year with taking thousands of dollars in payoffs in a scheme to put a Democratic state senator on the Republican ticket for mayor.